- The chronic GVH reaction is induced in inbred strains of mice by a transfer of spleen and lymph node T cells that recognize a foreign MHC class II determinant in the recipient. This syndrome is characterized by a spectrum of autoantibodies and immunopathological changes that closely parallels those found in human systemic lupus erythematosus. Previous work by the principal investigator's laboratory and others have shown that this disease is induced by the donor alloreactive T cells that recognize foreign MHC class II on B cells of the recipient that are in turn, induced to produce autoantibodies. In the current application, the principal investigator proposes to study the specific role of the donor and recipient T cells as well as the recipient B cells in chronic GVH. His specific aims are (1) To learn how B cell tolerance is lost in the chronic GVH reaction; (2) to understand what the role is of endogenous T cells in the chronic GVH response; and, (3) to determine what the role is of donor T cells in the chronic GVH response. These studies, the applicants expect, will provide important insight into the mechanism of autoantibody production and loss of tolerance in the chronic GVH response. This, they believe, will help in understanding the underlying mechanisms that produce the loss of tolerance characteristic of spontaneous systemic lupus erythematosus (SLE), both in mice and in humans. Such understanding will, eventually, lead to more rational therapy for this disease and other autoimmune diseases.